1. Field of the Invention
The present invention relates to a luminous gas-discharge sign panel and more particularly to a panel type "neon sign" devised so that its individual sign pattern constituting elements may bright evenly irrespective of their widths.
2. Prior Art
A commonly called "neon sign" is usually made up of a sign or a plurality of bend-worked gas-discharge tubes of glass. As a matter of course, a gas-discharge tube must be constituted by a continuous discharge path, therefore, if a sign pattern, as is often the case, consists of a plurality of pattern-constituting elements, the pattern must be constituted either with a plurality of gas-discharge tubes or with a partially light-shielded single gas-discharge tube. The use of many discharge tubes results in the complexity of tube arrangements and electric wirings, whereas partial light shielding, practiced usually with bad-looking opaque bandage or coatings applied to the tube, injures the beauty of the neon sign, particularly in the daytime when the neon sign is kept non-luminous. Besides, the gas-discharge tubes themselves are not only fragile but also unsuitable for the mass-production of the same-patterned neon sign.
To overcome the above disadvantages, panel type neon signs have been proposed, for example, in U.K. Pat. No. 400,646 and Canadian Pat. No. 592,921. However, the panel type neon signs disclosed in these patent documents still have many important disadvantages, and probably under such circumstances they have not yet been put into practice. In the U.K. patent, for example, an interposed sheet made of a material such as cellulose is used between a front and a rear plates to stick them together, both the plates being provided with grooves forming a discharge path. In such a construction the outgases from the interposed cellulose sheet come to prevent a normal discharge and make the product impractical. On the other hand the Canadian patent has a problem in welding the front and the rear plates, namely in the method of glass work.
The inventor of the present patent application also proposed an improved panel type neon sign in Japanese Utility Model Publication No. 57-60050, and has already succeeded industrially and commercially in putting it into practice. However, this also has a disadvantage that the width of the individual luminous elements constituting a sign pattern must be constant throughout the whole length of the pattern for an even or uniform brightness of the sign. In addition this panel type neon sign also has a disadvantage that its appearance in the daytime is not completely free from being injured aesthetically by an interference between the ambient light reflections from the front and back plates constituting the sign panel.